Modified Polypropylene Laminate Interlaminar Bond Strength
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Solution Overview
Problem
Polypropylene resins have high gas permeability, making them unsuitable for packaging materials requiring high gas barrier properties, and existing laminates with improved barrier properties suffer from weakened interlaminar bond strength during high-speed molding or stretch molding.
Innovation Solution
A modified polypropylene composition comprising 60-85% propylene-based polymer, 10-30% ethylene/α-olefin copolymer, and 0.01-10% graft-modified polypropylene with unsaturated carboxylic acid derivatives, enhancing interlaminar bond strength and enabling high-speed molding and stretch molding without compromising gas barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polypropylene resin is used for packaging materials, then mechanical strength and rigidity are improved, but gas barrier properties deteriorate
Solution Approach 1:
The patent applies composite materials by creating a multilayer laminate structure combining polypropylene resin with other resins having different properties. Specifically, it uses a three-layer structure where the middle layer contains polypropylene resin with grafted unsaturated carboxylic acid or anhydride, and the outer layers contain resins with good gas barrier properties, achieving both mechanical strength and gas barrier performance through material composition
2Strength
If bonding resin is co-extruded to enhance interlaminar bond strength, then bond strength between layers is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the bonding resin function into the polypropylene resin itself by grafting unsaturated carboxylic acid or anhydride onto the polypropylene chains. This eliminates the need for separate bonding resin layers while maintaining excellent interlaminar adhesion, simplifying the overall structure from a potential four-layer system to a three-layer system where the middle layer performs both structural and bonding functions
3Productivity
If molding rate is increased to improve productivity, then production efficiency is improved, but interlaminar bond strength deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the polypropylene resin by introducing grafted unsaturated carboxylic acid or anhydride groups, which fundamentally alters the bonding mechanism. This chemical modification enables the resin to maintain excellent adhesion properties even at high molding rates, as the grafted groups provide strong chemical bonding capability that is not dependent on slow processing conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified polypropylene composition significantly enhances interlaminar bond strength, allowing for the production of laminates with excellent gas barrier properties suitable for applications like food and pharmaceutical packaging, even under high-speed and stretch molding conditions.
Implementation Method 1
a propylene-based polymer (A-1), 10 to 30% by weight of an ethylene/α-olefin copolymer (B) and 0.01 to 10% by weight of modified polypropylene (C) a part or all of which has been graft-modified with an unsaturated carboxylic acid or a derivative thereof
Data Source
AI summary
It is an object of the present invention to provide a modified polypropylene composition for forming laminates, which enables prevention of lowering of interlaminar bond strength even in the case where it is subjected to high-speed molding or subjected to stretch molding, and a laminate using the composition and having excellent interlaminar bond properties. The present invention relates to a modified polypropylene composition comprising a propylene-based polymer (A-1), 0 to 45% by weight of a propylene-based polymer (A-2), an ethylene/α-olefin copolymer (B) having a melt flow rate (MFR; ASTM D1238, 230° C., load of 2.16 kg) of 0.01 to 40 g/10 min and a density (ASTM D1505) of not more than 0.900 g/cm3, and a specific amount of modified polypropylene (C) a part or all of which has been graft-modified with an unsaturated carboxylic acid or a derivative thereof.